Hydrodynamic transmission



Dec. 28, 1948. L. E. LA BRIE 2,457,692

HYDRODYNAMIC TRANSMISSION 7 Original Filed Dec. 10, 1941 3 Sheets-Sheet 1 INVENTOR ATTORNIHB,

Dec. 28, 1948. L. E. LA BRIE 2,457,692 v amnonmmrc TRANSMISSION Original Filed Dec. 10, 1941 I 1 s sheets-sheet 2- [1V VEN TOR l I I llzafgerlal'i'rz'e.

A TTORNE Y5.

Dec. 28, 1948. E. LA BRIE HYDRODYNAMIC TRANSMISSIQN 3 Sheets-Sheet 3 Original Filed Dec. 10, 1941 Patented Dec. 28, 1948 HYDRODYNAMIC TRANSMISSION Ludger E. La ,Brie, Detroit, Micln, assignor to Chrysler Corporation,

Highland Park, Mich ,a corporation of Delaware Original application December 10. 1941, Serial No.

422,369. Divided and this application Decemher c, 1943, Serial No. 513,081

18 Claims. (01. 74-1895) This invention relates to power transmissions and controls therefor and is especially concerned with fluid power transmission mechanisms. The application is a division of my copending application Serial No. 422,369, flled December 10, 1941, now abandoned.

In power transmissions employing fluid power transmitting devices the problem of cooling under heavy load conditions has been an important consideration. This has been particularly true where the fluid power transmitting device was of the torqueconverter type. vIn this connection, previousattempts to eliminate cooling tanks for the torque converter fluid have been generally unsuccessful because the fluid heats rapidly during operation'of the converter for torque multiplication, and, if the converter is called upon to multiply torque for the purpose of ascending long hills and the like, the heating 4 may be excessive. A

The chief object of my invention is to provide means for preventing excessive heating of the fluid in fluid power transmitting devices especially those of the torque converter type.

It is also an object of my invention to provide means for automatically decreasing the load on the fluid power transmitting device when abnormal temperature conditions prevail in the fluid of such device. v r

A further object is to provide change speed mechanism for operation in conjunction with a fluid power transmitting device which is adapted for conditioning to decrease the load on the fluid,

power transmitting device when abnormal heat conditions prevail in the fluid of such device.

Another object of my invention is to provide a novel control mechanism responsive to temperature of the fluid in a fluid power transmitting device for automatically conditioning a change speed mechanism to reduce the load on suchdevice at or above a predetermined temperature of such fluid.

The present invention preferably employs a fluid power transmitting device of the torque converter type and I have designed the vanes and wheels of this unit in such manner that the range oi torque multiplication thereof is comparatively short, in the order of zero to 15 M. P. H. at full throttle. .A gear transmission of the kickdown type is used with the converter and means is provided for effecting a stepdown in ratio whenever the temperature of the converter fluid rises above a predetermined maximum. The speed of the converter is thus increased and the load demand is less because of the torque mul- Accordingly, furhydraulic fluid is tiplication through the gears. thcr temperature rise in the, that prevented.

Other objects and advantages of my invention will become more apparent from the following description taken in conjunction with the accompanying drawings wherein I have illustrated a preferred embodiment of the invention. Fig. 1 is a vertical sectional view of the'upper portion of the forward part of the transmission. Fig. 2 is avertical section of the rear part or gearbox.

Fig. 3 is an enlarged detail of the synchrosleeve and its associated parts. 18 Fig. 4 is a partial view of a vehicle power plant embodying the invention.

Fig. 5 is a diagrammatic view of the control mechanism for the synchro-sleeve, the latter being shown in its released position. 80 Fig. 6 is a similar view of a portion of the Fig. '5

control mechanism in engaged position.

In the drawings, A represents the vehicle engine, B the torque converter, C a drive-releasing clutch and D the kickdown gearing.

The engine A has a crankshaft In to which is fastened by bolts li, a housing shell l2 which carries air impelllng flns l3. Secured to the shell by cap screws I4 is a fluid impeller I5.

30 A starting ring gear 16 forms part of the joint adapted for engagement by the usual motor driven starting pinion (not shown).

The impeller I5 is provided with outer air impelling fins I1 and an inner shell member 18 35 which carries a plurality of fluid impelling vanes ID. The latter are attached to the member 18 by tabs 20 and a torus ring 2| is welded or otherwise suitably fastened to. the inner peripheral edges of the vanes as illustrated. The impeller I! has an inwardly tapered rear portion 22 provided with screw threads 23 adapted to receive and secure a fluid seal element 24.

A runner or turbine wheel 25 provided with vanes 26 is disposed in juxtapositioned driving 45 relationship with the impeller l5 and a guide or reaction wheel 21 which has vanes 28. The runner is carried'by a hub 28 which is splined on a shaft 30, an anti-friction bearing 32 separating the hub 29 from the impeller hub 3|. The guide wheel 21 is splined on a hollow shaft 33 which has a forward enlarged portion 34 separated from the hub 29 by an anti-friction bearing 35.

Thehollow shaft 33 terminates rearwardly in a reduced portion 36 which is separated from the shaft by a bushing 31 and forms one part of between the housing parts l2 and I5 and is an overrunning roller brake 33. The brake 38 also includes a stationary member 39 bolted to the inner casing extension 40 by bolts M and a set of rollers 42. The brake 3B is of the reverse lock type and functions in a manner well known in the art to prevent reverse rotation of the shaft 33 and guide wheel 21 while permitting free forward rotation thereof.

The stationary member 39 also carries a hearing 43, the inner race of which surrounds the enlarged hollow portion 44 of the shaft 3d.

Disposed adjacent the bearing 35 is an overrunning clutch 55 which includes rollers 46 and a member ill splined to the shaft 30. The clutch 35 is adapted to permit the shaft 38 to overrun the guide wheel 21, and to clutch the guide wheel to said shaft upon tendency of the former to overrun the shaft.

A second overrunning clutch 48 of the reverse loci: type is drivingly disposed between the impeller hub 3i and the shaft 36. This clutch includes rollers t9 and a clutch member El! and functions to permit the impeller is to overrun the shaft in the forward direction of rotation and to establish a driving connection therebetween upon tendency of the shaft 3D to overrun.

Between the shafts 3B and 33 is disposed a seal i. This seal may but preferably includes a flexible bellows 52' secured at its ends to annular rings 63 and lit. The

former has a screw threaded connection with the shaft 33 and the latter is adapted to bear against a ring 55 which in turn bears on a ring 56 carried by the shaft 30. A spring 5% acts between the ring 54 and a member 5'! carried by the threaded ring 53 and maintains a fluid tight fit between the rings 56, 5E and 56. The ring 65 floats between the rings 55 and 58 and has a lapped surface on each side thereof which bears on similar lapped surfaces of the rings 58, B6.

A similar type of seal, designated 5?, is disposed between the shaft 33 and the impeller it. The seal 5? comprises a floating ring 58 which floats between rings 59 and 60, the latter being attached to bellows Bl. The other end of the bellows is secured to the member 24 and a spring 62 acts to press the rings 58. 59, 60 together.

It will thus be seen that the hydraulic converter is sealed ofi from the clutch C and gearing D by the seals 5! and 51, the springs 58 and 62 thereof being of sufiicient strength to prevent escape of the converter fluid unless the pressure rises to an unsafe value.

During the torque multiplying stage of converter operation, the guide wheel Zl is stationary (the brake 38 being engaged) and the runner 25 "slips" with respect to the impeller i5 which is of course driven at engine speed. Under such conditions there is 100% slip between the impeller and guide wheel and between the runner and guide wheel. However, as soon as torque demand on shaft 30 decreases to a point where the reverse rotational tendency of the guide wheel disappears, the guide wheel begins to rotate forwardly as permitted by the overrunning brake 42; thus the slip on the seals El and El is rapidly reduced.

As is characteristic of torque converters of the Tri-lock" type, the guide wheel accelerates rapidly upon beginning forward rotation until it reaches the speed of the runner 25 whereupon the roller clutch 35 functions automatically to lock the guide and runner wheels together. The torque converter then functions as an ordinary be of any suitable type,

4 fluid coupling of the kinetic type and the slip-on seal BI is zero.

As the vehicle accelerates in speed accompanied by decreased torque demand. the runner gradually approaches the impeller in speed until crulsing condition is reached. At cruising speeds, the slip between the impeller i5 and the two-part runner is in the order of 3% and the seal 51 is thus relieved. 1

when the vehicle is stationary with the clutch C engaged, the slip on seal 5| is zero because the runner and guide wheel are both stationary and the slip on seal 51 is During normal vehicle operation, the period of slip between the runner and guide wheel is short because the hydraulic wheels are preferably designed such that the range of torque multiplication ends at approximately 15 M. P. 3., thus the seal M is subjected to relative rotation for an extremely small percentage of vehicle operating time.

While there is always some slip between the impeller and the guide wheel, it is in the order of 3% at cruising speeds which means that only 3% slip is efiective on the seal 61 during the major period of vehicle operation.

By means of this simple and ingenious arrangement of hydraulic wheels and seals, the wear on the seals is greatly reduced compared to oonvendated May 1, 19%, and it is deemed sufficient for purposes of the present description to state that the clutch comprises a driving element 69 fixed to the shaft 30 and a driven element 10 fixed to-the shaft 66. These two elements are adapted to be frictionally connected by a spring II which is expanded by a finger 12 carried by a pilot member 13. The pilot I3 is slidable by means of the released mechanism 14 and pedal 15. When the friction lining 18 of the pilot is engaged with the driving element 69 as shown in Fig. 1, a drive is transmitted from. shaft 30 to shaft 66. Upon tendency of the shaft 86 to overrun the shaft 30, as for example during coasting of the vehicle, the overruning roller clutch 'I'l functions to lock the two shafts together thereby preventing free wheeling and providing a two-way drive. While the servo clutch is'preferred, a conventional type of friction clutch may be substituted if desired.

Referring now to Figs. 2 to 6, inclusive, it will be seen that the drive pinion S1 is disposed in constant mesh with the gear 76 which drives a countershaft cluster ll through an overrunningclutch B8 of the usual type such that when shaft 66 drives in its usual clockwise'direction (looking Countershaft cluster TI comprises cluster gears 18' and 18 whichrespectively provide forward cluster gear 18', a hub 85 which carries a shiftable sleeve 88, and clutch teeth 81; A hub 88 is splined on the shaft 88 and carries therewith amanually shiftable sleeve 89 whi'chis adapted to be shifted by suitable remote shift mechanism (not shown) from its illustrated neutral position forwardly to clutch with the teeth 81, a blocker 88 being disposed between the sleeve 89 and the clutch teeth 81 to facilitate shifting and prevent clashing of teeth. p I

Shaft 88 also carries a reverse driven gear'9I which is fixed thereto. A reverse idler gear 92 is suitably mounted on its own countershaft such that when reverse drive is desired, idler 82 is shifted into mesh with the gears 19 and 9|.

Shifting of the reverse idler gear 92 is preferably controlled by the remote shift mechanism, thus it may be seen that forward drive or reverse drive may be obtained by selective manipulation of sleeve 88 and gear 92, clutch C being released by depression of the pedal when shifting into one of these drives.

The sleeve 88 is slidably splined on the hub portion 85 and is adapted to be shifted forwardly to clutch with teeth 83 formed integrally on the shaft 88 under control of a blocker 94. The sleeve 88 is adapted to be shifted by power means to step up the speed ratio from low speed drive to high speed drive, the latter being a direct drive through the. gearing.

When driving the car forwardly, the manual sleeve 89 is engaged with the clutch teeth 81 and the car is started in low speed drive ratio, the drive being from the shaft 88 through pinion 81, gears 18, 18' and 84, sleeves 89 and hub 88 to the shaft 88.

Power operated mechanism about to be described is operable under certain conditions of vehicle drive to shift the sleeve 88 forwardly to" clutch with the teeth 93 whereupon a direct drive between shafts 88 and 88 is obtained. This step-up in drive is accommodated through overrunning of the clutch 18 in response to driver release of the accelerator pedal as the desired speed has been reached whereupon the power mechanism will accomplish forward shift of the sleeve 88 when the rotational speed of the pinion 81 and clutch teeth 93 has been retarded to a speed synchronous with the speed 'of the sleeve 88.

A step-up in speed ratio during reverse driving may be accomplished in a similar manner by release of the accelerator pedal after a. predetermined speed in reverse has been reached: Thus a low speed reverse drive may be obtained through pinion 81, gears 18, 82 and 9| andja high speed reverse drive may be obtained through pinion 81, sleeve 88, gears 84, 18', 19, 92 and 9I.

The above described mechanism is more fully dmcribed'and illustrated in Dunn Patent No. 2,257,674, issued September 30, 1941.

The power means for controlling shift of the sleeve 88 comprises a pressure fluid operated motor G which utilizes air pressure for its operation. For convenience, this motor is arranged I to operate by the vacuum or suction of the intake manifold systenr of the. engine under control of electromagnetic means illustrated in the form of a solenoid H.

Forward shift of the sleeve 88 is effected under control ofmotor G by reason of a spring 88 fixed at one end and exertin a pull on lever 99 which is connected to the sleeve 88 through the cross shaft I88 and shifter yoke IIII. Pivoted to the lower end of the lever 98 is a follower rod I82 guided in thesupport I83 and in a rubber sealed booth I 84 carried by a cylinder I85 which contains a diaphragm I88 urged in a direction to release the sleeve 88 by a spring I81 which is -oi relatively greater strength than the spring 88. Diaphragm I88 is connected to a leader rod I88 which has a rear extension I89 aligned with the rod I82.

The rod I88 has a series of detents II8, III and H2, the latter cooperating with a latch H3 such that when vacuum is admitted to the chamber I to cause the piston I88 and rod I88 to assume their. Fig. 6 positions, latch II3 under action of rat trap spring II5 catches on the forward shoulder of detent H2 and holds the parts in Fig. 6 position. At this time rod portion I89 moves further than rod I82 by the amount of gap II8, a stop II1 acting on lever 99 limiting forward movement thereof under the influence of spring 88.

In order to provide for release of sleeve 88 thereby to secure an automatic step-down in gear ratio without necessitating release of the. clutch C; it is desirable to provide some means for momentarily relieving the torqueload at the teeth 83 and in the present instance, this means has been provided through grounding of the ignition system. This ignition interrupting system is under control of an ignition interrupter switch II8 which is closedby a plunger H9 and ball I28 whenever rod I88 moves between'its Fig. 5 and Fig. 6 positions by reason of the enlarged portion of the rod between the detents H8 and III. De-' tent I II is so arranged that with the parts in the Fig. 6 position and sleeve 88 clutched with clutch teeth 93, rod I88 may move rearwardly sufficiently to close the gap I I8 thus taking up the lost motion between the rod portions I89 and I82 which movement of the rod I88 causes the switch I I 8 to close and ground the ignition system whereupon spring I81 will then cause further rearward movement of the rod I88 and rod I82 to release sleeve 88, the switch II8 opening as soon as the detent II8 comes under the ball I28.

7 The Vacuum supply to the chamber I I4 is under control of a solenoid H which comprises an armature plunger I28' having valve parts I2I, I22. In Fig. 5 the solenoid H is shown energized, the plunger I28 being raised against the spring I23 to seat the valve I22 and shut off the vacuum supply to the chamber I I4 while at the same time valve I2I is unseated so as to vent this chamber through the passage I24, chamber I25 and vent passage I28. When the solenoid is de-energized. then the spring I23 lowers the plunger I28 thereby seating valve I2I to shut off vent I28 and opening valve I22 as illustrated in Fig. 6 to thereby open chamber I I 4 to the intake manifold of the engine A through passage I24, chamber I25, chamber I28 and pipe I21.

A certain lost motion is provided between plunger I28 and the inwardly bent finger 3' of the latch I I3 so that when the plunger moves downwardly the latch may subsequently catch in the detent I I2 when the vacuum has operated the piston I106, the parts then remaining in Fig. 6 positionindependehtly of .the vacuum in chamber I I4 untii the solenoid His energized to release the latch and vent the chamber II4.

Preferably energization and de-energization of the solenoid H is controlledby a governor mechanlsm. This governor mechanism designated generally by the letter J is driven from the countershaft cluster gear I8, the governor being provided with a sleeve I29 which is thrust outwardly along the driveshaft I30 as the car speed reaches a predetermined value, the break-away being under control of a detent I3I.

The sleeve I29 has a shoulder I32 engaged by the swinging switch piece I33 of the governor switch I34. When the car is stationary, the detent I3l is engaged and the switch I34 is closed. As the car accelerates, the governor eventually reaches its critical speed and detent I3I releases, thereby causing switch I34 to open. As the car slows down, the governor spring I35 restores the parts to Fig. position and by suitably proportioning the various parts, it is obvious that the switch I34 may .be made to function at desired speeds proportionate to car travel. With the present transmission arrangement wherein the hydraulic torque converter provides torque multiplication'through a range up to approximately M. P. H., the governor J is preferably arranged to open the switch I34 at a speed in the neighborhood of 22 to M. P. H.,,thus providing a two stage acceleration range up to approximately 25 M. P. H. wherein both the hydraulic action and the gearing multiply torque during the first stage and the gearing alone multiplies torque during the second stage.

As the car slows down, the governor spring I restores the parts to the Fig. 5 position and by proportioning the various parts, it is obvious that the switch I33 may be made to function. At desired speeds proportionate to car travel, it is preferred to have the switch close in response to slowing down of the vehicle at a speed lower than that at which it opens upon acceleration of the vehicle. This prevents hunting and undesirable cyclic operation.

Referring now to Fig. 5, it will be seen that I have illustrated the control circuit for the transmission as well as a portion of the engine ignition circuit.

One side of the solenoid H is connected to the vehicle battery I36 through an ammeter I31, ignition switch I38, wire I39 and wire I40. The other side-of the solenoid is connected to ground through wires HI and I42, switch '3 and wire I44, the vehicle battery of course being grounded as is usual in automotive practice. The switch arranged to open the switch I43 when the accelerator pedal has been returned to substantially engine idle position.

A speed responsive switch I33 is connected by means of a wire I56 with the wire I 42. Thus it may be seen-that operation of the switch I 43 by depression of the accelerator pedal I to sub-' stantially wide open throttle position will overrule the switch I33 and energize the solenoid H. The driver is thus enabled to kickdown to a lower speed ratio at any time. Thus the increased torque multiplication made available by disengagement of the synchro sleeve 86 is instantly available. .1

In order to eifect release of the synchro sleeve 86 and step down in speed ratio, it is necessary that the drive of the engine be diminished momentarily so that the load on the teeth of the synchro sleeve will be released. This is accomplished in the present arrangement by grounding the ignition and the circuit for rendering the ignition momentarily inoperative will now be described. This circuit includes the switch II8 which is connected to ground through the kickdown switch I 43 [by means of wire I4I, the other side of the switch II8 beingconnected by wire I51 to the ignition coil I58. From Figs. 5 and 6, it may be seen that when the switch I43 is closed, solenoid H will be energized and as soon as the rod I08 has moved sufficiently to take up the gap II6, switch II8 will close thereby connecting the ignition coil I58 to ground through wires I4 I, I42 and I44.

Grounding of the ignition will immediately relieve the torque on the synchro sleeve 86 and permit the spring III! to shift the sleeve out of mesh with the clutch teeth 93 as has been described. As soon as the detent IIO comes underneath the ball I20 of the switch N8, the ignition will be restored and the vehicle will be driven in its low speed ratio at wide open throttle. As the finger I of the lever I46 does not engage the switch finger I45 tolopen the switch until the accelerator pedal I50 is returned to substantially idle position, the driver may drive the vehicle at any intermediate throttle opening in low speed drive 1 ratio for any length of time he desires. Release I43 is arranged to be operated by the vehicle accelerator pedal as illustrated in Fig. 4, it being seen from that figure that the., s'.wltch has an operating finger I45 adapted tobe operated by a lever I46 which is carried by lever I41. The latter is pivoted on the vehicle floor boards and has links I48 and I49 pivotally connected therewith. The link I48 is connected to be actuated by the vehicle accelerator pedal I50 and the outer end of the link I49 is pivotally connected to the throttle lever I52 01 the carburetor. A return spring I53 biases the accelerator pedal to engine idle position and the arrangement is such that when the accelerator pedal is depressed to substantially wide open throttle position, the finger I54 of lever I46 will engage the operating finger I45 of the switch I43 thereby to close the switch. A second finger I55 formed on the lever 146 is of the accelerator pedal under such conditions that the vehicle will coast will result in automatic engagement of the synchro sleeve through operation of the solenoid H and servo motor G as aforesaid providing that the speed of the vehicle is above the cut-in speed of the governor mechanism J.

It will be noted that the ignition is grounded through the speed responsive switch I33 in a. manner similar to that just described when the latter switch closes in response to slowing down of the vehicle.

Referring now to Figs. 1 and 5, it will be seen that a temperature responsive switch I60 is disposed within the casing shell I5 of the torque converter fluid. This switch comprises a bimetallic element I6I which is connected by means of a wire I62 with the conductor I42 which leads to the main solenoid energizing and ignition grounding circuit. The bi-metallic element I6I is adapted to engage a terminal I63 which is connected to ground through a wire I64. As illustrated in Fig. 1 the wires I62 and I64 are actually connected to the switch I60 by means of a pair of slip rings I65, I66.

The switch I60 is arranged such that the bi-' metallic element I6I will close the switch should the temperature of the fluid and/or gases in the speed ratio is eflected in response to attainment of abnormal temperature within the-torque converter and as the step-down to lower speed ratio will result in the speeding up of the torque converter as a whole, more air will be drawn in through the housing by the air impelling vanes l3 and H which will result in a cooling of the torque converter and in addition the load thereon will be relieved because of the torque multiplica tion afforded by the gearing.

It may thus be seen that I have provided a simple form of automatic transmission embody? ing a hydraulic torque converter which is arranged in such manner that it has a relatively short torque conversion range in view of which air cooling of the converter may be resorted to;

As a safety feature, I have provided means for securing automatic step-down in the gear box portion of the transmission in response to the attainment of abnormally high temperature in the torque converter- I claim:-

1. In a power transmission for a vehicle having an engine, a fluid power transmitting .device drivingly connected to the engine, change speed means drivingly connected to said device-and adapted to provide a plurality of different speed ratio drives for said vehicle, and means including control means operative in response to departures from the normal operating physicalcondition of the fluid in said device and operable at a premember in said determined condition of said fluid for effecting a change in the speed ratio drive of said vehicle.

2. In a power transmission for a vehicle having an engine, a fluid power transmitting device drivingly connected to the engine, change speed means drivingly connected to said device and adapted to provide a plurality of different speed ratio drives for said vehicle, and means including control means arranged as to be subject to the influence of temperature changes in the fluid of said device and operable at a predetermined temperature condition of the fluid in said device for effecting a shift in said change speed mechanism from a higher to a lower speed ratio drive.

3. In a power transmission for a vehicle having an engine, a fluid power converter of. a type 1 adapted to provide a torque multiplying drive and a slip coupling drive for said vehicle, and including a rotatable impeller member and a runner member, one of said members including means for cooling said converter, temperature responsive means responsive to changes in the temperature of the fluid in said device and means operable in response to operation of said temperature responsive means at or above a predetermined temperature of said fluid for decreasing the engine load whereby to enable an increase in the rotative speed of said converter member including said cooling means, for inhibiting substantial further increase in the temperature of said fluid.

4. In a power transmission for a vehicle having an engine, a fluid power transmitting device drivingly connected to the engine, change speed means drivingly connected to said device, and adapted to provide a plurality of different speed ratio drives for sponsive means positioned in contact with the fluid of said device and operable at or above a predetermined temperature of said fluid for tat--v fecting a change in the speed ratio drive of said vehicle.

5. In a power transmission which includes a fluid power transmitting device and change speed gearing, power operated means for eflecting stepup and step-down in speed ratio in said searing:

and means operable in response to fluid temperature in said fluid power transmitting device for controlling said power operated means.

6; In a power transmission which includes a fluid power-transmitting device and ,change speed gearing, power operated means for efiecting step.

up and step-down in speed ratio in said gearing; and means for'causing. step-down in speed ratio automatically in response to attainment of abnormal temperature in said fluid power transmitting device. 1

7. In a power transmission comprising a fluid coupling and a gearbox arranged in tandem, a gearbox adapted for shifting be tween high-speed and low-speed positions; power operated means for shifting said member; control means for said power operated means; and temperature responsive means disposed within said fluid coupling operatively associated with said control means.

8. In a power transmission for-a vehicle having an engine-a fluid coupling and a gearbox arranged in tandem, a member in said gearbox adapted for shifting between high-speed and lowspeed positions; power operated means for shifting said member: control means for said power operated means, including means for effecting momentary diminution in engine torque whereby said membercan be shifted from high-speedto low-speed position during driving, and means operable in response to abnormal-temperatures in said coupling for causing operation of said control means.

9. In a-power transmission having a fluid power transmitting device and change speed means.

fluid of said device, and means for controlling.

said power means including heat responsive means carried by said device.

10. A power transmission for a motor vehicle comprising a casing shell for holding fluid, a hydraulic pump wheeLand a hydraulic turbine wheel for operation in said fluid, means for varying the vehicle load on said pump wheel and temperature responsive means carried by one of said casing and wheels and responsive to heat changes in the fluid for operating said to reduce the vehicle load on said pump Wheel whereby to facilitate an increase in the rotative speed of said wheels.

11. A power transmission for a motor vehicle comprising a casing shell for holding fluid, a hydraulic pump wheel and a hydraulic turbine wheel for operation in said fluid, means for varying the vehicle load on said pump wheel and a thermostatic switch disposed within the casing shell and responsive to heat changes in the fluid for operating said load varying means to reduce the vehicle load on said pump wheel whereby to said vehicle and temperature reload varying means facilitate an increase in the rotative speed or said wheels.

12. A power transmission for a motor vehicle comprising a casing shell for holding fluid, a hydraulic pump wheel and a hydraulic turbine wheel for operation in said fluid, means ior varying the vehicle load on said pump wheel and means for controlling said load varying means comprising a thermostatic switch disposed within the casing shell, a pair of slip rings carried outside said shell, and circuit means connecting said switch and slip rings, said switch being operably responsive to heat changes in the fluid.

13. In a power transmission for a vehicle having an engine, a fluid power transmitting device drivingly connected to the engine and including a fluid retaining shell, a change speed mechanism drivingly connected to said device and adapted to provide a plurality of diflerent speed ratio drives for said vehicle, means for efle'cting a change in the speed ratio drive setting or said change speed mechanism. power means including a solenoid for operating said change effecting means, and control means for controlling said power means to effect a change in said change speed mechanism from a higher to a lower speed ratio drive upon an abnormal heat condition prevailing in the fluid of said fluid power transmitting device including a thermostatic switch disposed within said shell, a pair of slip rings disposed outside said shell, and circuit forming means between said switch and rings and between said rings and said power means.

14. In a power drive for a vehicle having an engine, a fluid power transmitting device drivingly connected to said engine and to the vehicle driving wheels, the fluid in said device having a normal operating temperature, temperature responsive means disposed as to' be responsive to temperature changes in said fluid and operable at a predetermined abnormal temperature or said fluid, change speed means drivingly connected between said fluid device and vehicle driving wheels and having a high and a low speed ratio. said change speed means being operable in response to operation of said temperature responsive means to establish low speed ratio therein for facilitating a return of the temperature condition of said fluid to normal.

15. In a power drive for a vehicle having an engine, a fluid power transmitting device drivingly connected to said engine and to the vehicle driving wheels, the fluid in said device having a normal operating temperature, temperature re-,

sponsive means disposed as to be responsive to temperature changes in said fluid and operable at a predetermined abnormal temperature of said fluid and change speed means drivingly connected between said fluid device and vehicle driving wheels operable in response to operation of said temperature responsive means for facilitat- '12 ing a. return of the temperature condition of said fluid to normal.

16. In a power transmission for a vehicle having an engine, a fluid power transmitting device drivingly connected to said engine and to the vehicle driving wheels, temperature responsive means disposed in contact with the fluid or said device and operable at a predetermined temperature of said fluid, and means operable in response to operation of saidtemperature responsive means for eflecting a change in the operative condition between said engine and vehicle driving wheels to facilitate a change in the temperature conditioner said fluid.

1'1. In a power transmission for a vehicle having an engine, a fluid power transmitting device drivingly connected to the engine, and to the vehicle driving wheels, temperature responsive means responsive to changes in the temperature of the fluid in said device, and means operably associated with said device automatically operable in response to operation of said temperature responsive means at a predetermined temperature of said fluid for effecting a decrease in the engine load to thereby facilitate an increasein the rotative speed of said device.

18. In a power transmission for a vehicle having an engine. a fluid power transmitting device drivingly connected to said engine and to the vehicle driving wheels, the fluid in said device having a normal operating temperature, temperature responsive means disposed as to he responsive to temperature changes in said fluid and operable at a predetermined abnormal temperature of said fluid, and clutch means operable in response to operation of said temperature responsive means for effecting a change in the operative condition between said engine and vehicle driving wheels to facilitate a change in the temperature condition or said fluid.

LUDGER E. LA BRIE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

